Temperature Sensitivity And Differential Proteomics Of Puccinia Striiformis F.sp.tritici Under Heat Shock

Wheat stripe rust, caused by Puccinia striiformis f.sp. tritici(Pst) is one of the most important diseases in the world. In recent years, the populations of Pst has enhanced adaptation to higher temperature with global climate change. In this study, to define relationships of virulence, genetic diversity and temperature sensitivity, 78 isolates of Pst isolates with known ET50 value collected from 6 Chinese provincial areas in growing season of wheat during 2010-2011, were analyzed for virulence and genetic diversity by using 21 near isogenic lines with known resistance genes and AFLP technique, respectively. To illuminate the high temparature endurance mechanism of Pst on histological and proteomic level, Pst isolates with different temperature sensitivity were selected to analyse their external germination, infection progress and differential proteomics. The results are as follows:1. The relationships of virulence, genetic diversity and temperature sensitivity of Pst isolatesThe results of test for virulence diversity at seedling stage indicated that the Nei’s gene diversity(H) of virulence in Gansu was the highest(H = 0.2693),and the lowest was in Yunnan(H =0.1504). The genetic diversity result showed that, the Nei’s gene diversity(H) based on AFLP was between 0.1255 and 0.1653, the genetic identity(GI) was between 0.9647 and 0.9872, and the genetic distance(GD) was between 0.0129 and 0.0360. The correlation analysis showed that virulence diversity was significantly and negatively correlated with the average value of ET50, and positively correlated with the coefficient of ET50 variation, but not significantly correlated with genetic diversity.2. The biological characteristics of Pst isolates with different temperature sensitivityFour isolates( two high-temperature tolerance strains and two temperature sensitive isolates) were chose for gemination analysis under the temperatures of 10℃, 15℃, 20℃, 25℃. We found that high-temperature tolerance isolates germinated earlier and had much higher germination rate than temperature sensitive isolates under heat stress. Although the germinations of Pst with different temperature sensitivity were both above 80% at optimum temperature when germinating for 24 hours, the germination rate of temperature sensitive isolates at 3 h was less than 10% whereas the high-temperature tolerance isolates was between 65-80%. The germination rate of temperature sensitive isolates deceased dramaticly as temperature increased, and the germinations of it were less than 20% at 25℃ while it was above 90% for the high-temperature tolerance isolates.By the infection progress observation of isolates with different temperature sensitivity under heat stress, we found that the formation of haustorial mother cell and haustorium at 21℃ was later than 10℃; There was little difference in hypha branching number, colony length, haustorial mother cell number and haustorium number for high-temperature-tolerance isolates between 10℃ and 21℃, but significant difference for temperature sensitive isolates; High-temperature tolerance isolates displayed much more of hypha branching, colony, haustorium mother cell, haustoria and faster of infection process than isolates of temperature sensitive isolates at 21℃ for 48 hours to 96 hours,. The results above suggested highly temperature adoptation and aggressiveness for high-temperature tolerance isolates at high temperature.3. The proteonomic differences of Pst isolates with different temperature sensitivityIn order to understand the change of the proteome during heat stress of high-temperature tolerance Pst, proteins from germinated spores of one high-temperature tolerance strain were isolated and quantified by i TRAQ(isobaric tags for relative and absolute quantitation) technology. Among the 2575 proteins identified, there were 87 and 123 proteins up- and down-regulated during heat stress, respectively. Heme-binding peroxidase, catalase, thioredoxin reductase involved in response to oxidative stress and removal of superoxide radicals were up-regulated, which could recover the steady state of intracellular redox and physiological activity, and GTP-binding protein YPT1, GTP-binding protein YPT3, AGC protein kinase involved in response to stimulus were up-regulated as well. Phosphoenolpyruvate carboxykinase and glucose-6-phosphate isomerase involved in glycolysis were up-regulated, which could provide energy for Pst during heat stress. Phosphoglucomutase, 3-isopropylmalate dehydrogenase, enolase, inorganic pyrophosphatase involved in magnesium ion binding were up-regulated, which could keep the physiological and biochemical reactions normal.